Semiconductor device and manufacturing method thereof

ABSTRACT

A semiconductor device includes a substrate, and a gate electrode formed on the substrate on a gate insulation film. The semiconductor device also includes a source diffusion layer and a drain diffusion layer which are formed on the substrate where the gate electrode is sandwiched between the source diffusion layer and the drain diffusion layer, one or more source contacts formed on the source diffusion layer; and one or more drain contacts formed on the drain diffusion layer. At least one of the source contacts and the drain contacts includes a first contact region having a first size and a second contact region having a second size larger than the first size on the same source diffusion layer or on the same drain diffusion layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No. 13/917,989, filed Jun. 14, 2013, which is based upon and claims the benefit of priority from Japanese Patent Application No. 2013-003608, filed Jan. 11, 2013. The entire contents of both applications are incorporated herein by reference.

FIELD

Embodiments described herein relate to a semiconductor device and a manufacturing method thereof.

BACKGROUND

The generation (technical node) of semiconductor devices has currently advanced through the 90 nm generation, the 64 nm generation, the 45 nm generation, the 32 nm generation and the 22 nm generation node. Further, the 28 nm generation (which is the half-node of the 32 nm generation) has been attracting attention as the design architecture and semiconductor manufacturing technique which is equivalent to the 32 nm generation node. However, although a critical layer to which the strictest design criteria is applied can be manufactured by performing a single exposure in the 32 nm generation, at 28 nm and succeeding generations, because of inherent physical limits which occur by single exposure of a feature, critical layers cannot be manufactured unless double exposure is performed, i.e., the feature must be created by twice exposing the resist, and then etching an underlying hard mask and to be etched layer.

For example, at the 28 nm generation and succeeding generations, the double exposure becomes necessary when forming a hole for a contact plug (hereinafter referred to as a “contact”). However, to reduce manufacturing costs of the semiconductor device, an attempt has been made to manufacture a contact in the 28 nm generation and succeeding generations when performing single exposure by changing the number of contacts or a size of a contact at the time of preparing a photo mask. However, when the single exposure is replaced with the double exposure in this manner, there arises a drawback in that irregular layout dependency is observed in an FET manufactured by the single exposure, and such layout dependency differs from the layout dependency of an FET manufactured by double exposure. In this case, the design and an operation verification result of the FET manufactured by double exposure cannot be utilized by the FET manufactured by single exposure and hence, it is necessary to perform operation verification independent, i.e., different from, the operation verification methodology performed on the FET manufactured by single exposure.

Further, there exists a situation where it is desirable that the same design parameters as the 32 nm generation are used at the 28 nm generation node. However, because the above-mentioned drawback exists, an operational characteristic of an FET of the 28 nm generation manufactured by single exposure becomes different from an operational characteristic of an FET of the 32 nm generation manufactured by single exposure (similar to an operational characteristic of an FET of the 28 nm generation manufactured by double exposure) and hence, the 28 nm generation cannot use the same design parameters as the 32 nm generation. As a result, the design and the operation verification methodology of the FET of the 32 nm generation cannot be utilized by an FET of the 28 nm generation and hence, also in the 28 nm generation, it is necessary for the 28 nm generation to perform the operation verification independently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A to FIG. 1F are plan views showing the layout or pattern of structure based upon design data of a semiconductor device according to a first embodiment.

FIG. 2A is a plan view showing the structure of the semiconductor device shown in FIG. 1F, and FIG. 2B is a cross-sectional view showing the structure of the semiconductor device shown in FIG. 1F.

FIG. 3A to FIG. 3F are plan views showing the structure of a conventional semiconductor device.

FIG. 4 is a graph for comparing the operations between the semiconductor device of the first embodiment and the conventional semiconductor device of FIG. 3A to FIG. 3F.

FIGS. 5A and 5B are plan views showing the structure of a semiconductor device according to a second embodiment.

FIG. 6 is a flowchart showing a manufacturing method of a semiconductor device of according to one embodiment.

DETAILED DESCRIPTION

In general, according to one embodiment, the semiconductor device includes a substrate, and a gate electrode formed on the substrate on a gate insulation film. The semiconductor device also includes a source diffusion layer and a drain diffusion layer which are formed within the substrate, wherein the gate electrode is sandwiched between the source diffusion layer and the drain diffusion layer. One or more source contacts are formed on the source diffusion layer, and one or more drain contacts are formed on the drain diffusion layer. At least one of the source contact and the drain contact includes a first contact region having a first size and a second contact region having a second size larger than the first size on the same source diffusion layer or on the same drain diffusion layer.

Hereinafter, embodiments are explained in conjunction with the drawings.

First Embodiment

FIG. 1A to FIG. 1F are plan views showing the pattern of structures of a semiconductor device according to the first embodiment. FIG. 1A to FIG. 1C show three examples of the layout or pattern of structures to be formed based upon design data of the semiconductor device according to the first embodiment. On the other hand, FIG. 1D to FIG. 1F show the resulting formed structures of the semiconductor device when actually manufactured based on the design data shown in FIG. 1A to FIG. 1C, respectively.

FIG. 2A and FIG. 2B are views showing the structure of the semiconductor device shown in FIG. 1F, wherein FIG. 2A is an enlarged plan view showing the structure shown in FIG. 1F, and FIG. 2B is a cross-sectional view of the structure of FIG. 2A taken along a line I-I′ in FIG. 2A.

The semiconductor device of this embodiment is explained in detail by reference to FIG. 1 hereinafter, and the explanation is also made by reference to FIG. 2, when necessary.

All drawings from FIG. 1A to FIG. 1F show one FET which is included in a semiconductor device according to this embodiment. The semiconductor device according to this embodiment includes, as constitutional elements of the FET, a substrate 1, a gate insulation film 2 (see FIG. 2), a gate electrode 3, a source diffusion layer 4, a drain diffusion layer 5, an interlayer insulation film 6 (see FIG. 2), one or more source contacts 11, one or more drain contacts 12, and a gate contact 13. Although the semiconductor device according to this embodiment may be a semiconductor device of the generation where double exposure is performed (any one of generations including the 28 nm generation and the generations which follow, i.e., having a device pitch of less than the 28 nm generation, for example), the semiconductor device according to this embodiment is manufactured by performing single exposure using a technique for manufacturing a semiconductor device of this generation. Thus, the semiconductor devices in the 28 nm generation, and succeeding generations, include the semiconductor device of the 28 nm generation and semiconductor devices of the generations which follow the 28 nm generation.

The substrate 1 is a semiconductor substrate such as a silicon substrate, for example. In FIG. 1, the X direction and the Y direction which are parallel to a main surface of the substrate 1 and are orthogonal to each other, and the Z direction which is perpendicular to the main surface of the substrate 1 are shown. The X direction and the Y direction correspond to the longitudinal direction of the gate and the channel width direction of the FET. Here, the substrate 1 may be an SOI (Semiconductor On Insulator) substrate.

The gate electrode 3 is formed on the substrate 1 with the gate insulation film 2 therebetween. The source diffusion layer 4 and the drain diffusion layer 5 are formed within the substrate 1 in a state where the gate electrode is positioned between, and at its sides, overlies the layers 4, 5. The interlayer insulation film 6 is formed on the substrate 1 so as to cover the FET. The source contact 11, the drain contact 12 and the gate contact 13 (shown in FIG. 2A only) are formed on the source diffusion layer 4, the drain diffusion layer 5 and the gate electrode 3 respectively within the interlayer insulation film 6.

(1) Detail of Source Contact 11 and Drain Contact 12

Next, the details of the source contact 11 and the drain contact 12 are explained by reference to FIG. 1 successively.

In FIG. 1A to FIG. 1F, for the structure of both the source contact 11 and the drain contact 12, a first contact region C₁ having a first size and a second contact region C₂ having a second size larger than the first size are shown in FIG. 2A.

In the design architecture shown in FIG. 1A, one first contact region C₁ is arranged on both the source diffusion layer 4 and the drain diffusion layer 5. In the same manner, in the semiconductor device shown in FIG. 1D, which corresponds to the semiconductor device shown in FIG. 1A, one first contact C₁ is arranged on each of the source diffusion layer 4 and the drain diffusion layer 5.

In the design architecture or layout of a semiconductor device shown in FIG. 1B, two first contact regions C₁ are arranged on (and contact, not shown) both the source diffusion layer 4 and the drain diffusion layer 5. On the other hand, in the actually manufactured semiconductor device using the layout of FIG. 1B as shown in FIG. 1E, which corresponds to the semiconductor device design or layout shown in FIG. 1B, one second contact region C₂ larger than the contact C1 of FIG. 1B is formed on (and contacts, not shown) each of the source diffusion layer 4 and the drain diffusion layer 5.

In the design architecture or layout of a semiconductor device shown in FIG. 1C, three first contact regions C₁ are arranged on both the source diffusion layer 4 and the drain diffusion layer 5. On the other hand, in the semiconductor device actually manufactured using the layout of FIG. 1C as shown in FIG. 1F, only one first contact region C₁ and one second contact region C₂, larger than the individual contact regions C1 of FIG. 1C, are arranged on both the source diffusion layer 4 and the drain diffusion layer 5.

The semiconductor device according to this embodiment is the semiconductor device of the generation where double exposure is performed and hence, it is difficult to form a plurality of first contact regions C₁ on the same source diffusion layer 4 or on the same drain diffusion layer 5 by performing the exposure one time in the same manner as the design architecture shown in FIG. 1B and FIG. 1C. The reason is that a distance between the first contacts C₁ is extremely small.

To overcome this drawback, in this embodiment, a photo mask is prepared, based on design architecture shown in FIG. 1B or FIG. 1C, for single exposure by replacing two first contact regions C₁ arranged on the same source diffusion layer 4 or on the same drain diffusion layer 5 with one second contact region C₂. In this embodiment, with the use of such a photo mask, the source contact 11 and the drain contact 12 can be predictably formed by performing the exposure one time.

As a result, in this embodiment, the semiconductor structures shown in FIG. 1E and FIG. 1F are manufactured based on the design data shown in FIG. 1B and FIG. 1C, respectively. For example, in the semiconductor device shown in FIG. 1F, the source contact 11 includes both the first contact region C₁ and the second contact region C₂ on the same source diffusion layer 4 and, in the same manner, the drain contact 12 includes both the first contact region C₁ and the second contact region C₂ on the same drain diffusion layer 5.

Symbol X₁ indicates a length of the first contact region C₁ to be actually manufactured in the X direction (longitudinal direction of the gate), and symbol Y₁ indicates a width of the first contact region C₁ to be actually manufactured in the Y direction (channel width direction). Further, Symbol X₂ indicates a length of the second contact region C₂ that is actually formed on the substrate in the X direction, and symbol Y₂ indicates a width of the second contact region C₂ that is actually formed on the substrate in the Y direction.

In this embodiment, the length X₂ is set substantially equal to the length X₁, while the width Y₂ is set wider than the size Y₁. Due to such a constitution, in this embodiment, the size (volume) of the second contact region C₂ is greater than the size (volume) of the first contact region C₁.

(2) Resistances R₁, R₂ of First and Second Contact Regions C₁, C₂

Next, the detail of a resistance R₁ of the first contact region C₁ and a resistance R₂ of the second contact region C₂ is explained also by reference to FIG. 1.

As described previously, in this embodiment, in manufacturing the semiconductor device based upon the design data, two first contact regions C₁ arranged on the same source diffusion layer 4, or on the same drain diffusion layer 5, are replaced with one second contact region C₂. In this case, there arises a drawback that the resistance of the source contact 11 or the resistance of the drain contact 12 is changed before and after the replacement. This change adversely influences an operating characteristic of the FET (details of this drawback are explained later in conjunction with FIG. 4).

In view of the above, in this embodiment, to allow one second contact region C₂ to acquire a function substantially equal to a function performed by two first contact regions C₁, the resistance of one second contact region C₂ is set to a value substantially equal to the resistance generated when two first contact regions C₁ are connected to each other in parallel. Due to such setting, the relationship expressed by the following formula (1) is established between the resistance R₁ and the resistance R₂.

1/R ₂=1/R ₁+1/R ₁  (1)

To solve this formula (1), the resistance R₂ becomes ½ of the resistance R₁ (R₂=R₁/2).

Further, in this embodiment, the first contact region C₁ and the second contact region C₂ are formed using the same material. Accordingly, as expressed by the following formula (2), a ratio between the resistance R₁ and the resistance R₂ substantially corresponds to a ratio between the inverse number of an area X₁Y₁ and the inverse number of an area X₂Y₂.

R ₂ :R ₂=1/X ₂ Y ₂:1/X ₂ Y ₂  (2)

When substituting the formula (2) for the formula (1), the area X₂Y₂ then becomes two times greater than the area X₁Y₁ (X₂Y₂=X₁Y₁×2).

Accordingly, in this embodiment, by setting a size Y₂ to a value two times greater than a size Y₁, the area X₂Y₂ is set to a value approximately two times greater than the area X₁Y₁. In this embodiment, by setting the resistance R₂ to a value approximately ½ of the resistance R₁ in this manner, it is possible to allow one second contact region C₂ to acquire a function substantially equal to a function acquired by two first contact regions C₁.

However, in this embodiment, in general, the ratio between the resistances does not strictly correspond with the ratio between the inverse numbers of the areas which is expressed by the formula (2). One of reasons is that, as shown in FIG. 2B, a side surface of the source contact 11 and a side surface of the drain contact 12 are generally angled or inclined relative to a plane of the substrate 1. Further, in a case where planar shapes of the source contact 11 and the drain contact 12 to be manufactured actually are closer to a circular shape or an elliptical shape rather than a square shape or a rectangular shape, such shapes also cause the above-mentioned disagreement between the ratios.

Accordingly, in this embodiment, in setting the resistance R₂ to ½ of the resistance R₁, an area X₂Y₂ may not be simply set to an area two times greater than the area X₁Y₁, but the area X₂Y₂ is adjusted to an area in the range of or about the area which is twice as large as the area X₁Y₁ by finely adjusting the area such that the resistance R₂ approaches ½ of the resistance R₁. Such fine adjustment can be performed such that, for example, in preparing a photo mask, an area of the second contact region C₂ on the photo mask is finely adjusted, or Optical Proximity Correction (OPC) is applied to a pattern for a second contact region C₂ on the photo mask.

Further, in this embodiment, in manufacturing the semiconductor device based on design data, N (N being an integer of 2 or more) areas of the first contact region C₁ arranged on the same source diffusion layer 4, or on the same drain diffusion layer 5, may be replaced with one second contact region C₂. That is, as shown in FIG. 1, this embodiment is applicable not only to a case where two first contact regions C₁ are replaced with one second contact region C₂ but also to a case where three or more first contact regions C₁ are replaced with one second contact region C₂.

In this case, to allow one second contact region C₂ to have a function substantially equal to a function of N first contact regions C₁, the resistance of one second contact region C₂ is set to a value substantially equal to the resistance of N first contact regions C₁ which are connected to each other in parallel. That is, the resistance R₂ is set to 1/N of the resistance R₁. Such setting can be realized by setting the area X₂Y₂ to an area N times as the size of the area X₁Y₁ based on the relationship expressed by the formula (2).

In this case, by taking into account the instance where the formula (2) is not strictly established as described above, the resistance R₂ may have a tolerance of approximately ±10%. To be more specific, as expressed by the following formula (3), a value of the resistance R₂ is not always limited to R₁/N which is a parallel resistance of N first contact regions C₂, but may be set to a value of 0.9 times to 1.1 times as large as R₁/N.

0.9×R ₁ /N≦R ₂≦1.1×R ₁ /N  (3)

For example, in the instance where N is 2 (N=2) (in the case where two first contact regions C₁ are replaced with one second contact region C₂ as shown in FIG. 1), a value of the resistance R₂ is not always limited to R₁/2 (=0.5×R₁), but is set to a value which falls within a range of 0.45×R₁ to 0.55×R₁.

Further, in this embodiment, the first and second contact regions C₁, C₂ may be formed using only one kind of material, or may be formed using two or more kinds of materials. In the latter case, however, since a ratio between the resistance R₁ and the resistance R₂ depends on electrical resistivities of these materials, in general, it is necessary to take into account the electrical resistivities of the materials in adjusting the ratio between the resistances R₁, R₂.

(3) Comparison Between the First Embodiment and a Conventional Example

Next, by reference to FIG. 3 and FIG. 4, the semiconductor device of the first embodiment and the semiconductor device of a conventional example are compared.

FIG. 3A to FIG. 3F are plan views showing the layout or pattern of structure based upon design data of the semiconductor device of the conventional example and the structure of the semiconductor device of the conventional example to be actually manufactured. FIG. 3A to FIG. 3C show the design data which are equal to the design data shown in FIG. 1A to FIG. 1C respectively. Further, FIG. 3D to FIG. 3F show the structures of the resulting semiconductor device to be actually manufactured based on the design data shown in FIG. 3A to FIG. 3C, respectively.

In the conventional example, in the same manner as the first embodiment, it is difficult to manufacture a plurality of first contact regions C₁ arranged on the same source diffusion layer 4, or on the same drain diffusion layer 5, by performing exposure one time as in the design data shown in FIG. 3B and FIG. 3C.

Accordingly, in the conventional example, in preparing a photo mask based on design data shown in FIG. 3B, a photo mask for one-time exposure is prepared by replacing two first contact regions C₁ with one contact region C₁′ (shown in FIG. 3E) which is larger than the first contact region C₁

Further, in the conventional example, in preparing a photo mask based on the design data shown in FIG. 3C, a photo mask for one-time exposure is prepared by replacing three first contact regions C₁ with two contact regions C₁″ (shown in FIG. 3F) which are larger than each of the first contact regions C₁.

As a result, in this comparative example, the semiconductor device shown in FIG. 3E and FIG. 3F are manufactured based on the design data shown in FIG. 3B and FIG. 3C, respectively.

In this manner, in this example, in the same manner as the first embodiment, the replacement of the contact is performed when the semiconductor device is manufactured based upon design data. In this example, however, different from the first embodiment, in performing such contact area replacement, an operation to make a contact resistance before the replacement correspond with a contact resistance after the replacement is not taken into consideration. Accordingly, in this conventional example, as shown in FIG. 4, an operating characteristic of a FET is different before and after the replacement.

FIG. 4 is a graph for comparing the manner of operation of the semiconductor device of the first embodiment with the manner of operation of the semiconductor device of the comparative example described in FIGS. 3A-3F.

Bars P₁, P₂, P₃ show the drive currents of FETs in instances where the semiconductor devices are manufactured by double (two-time) exposure based on the design data shown in FIG. 1A to FIG. 1C, respectively. Here, values of all drive currents expressed by the bars P₁, P₂, P₃ are values obtained by dividing values of the drive currents of the FETs by values of the drive currents of the FETs in the semiconductor devices manufactured by double exposure based on the design data shown in FIG. 1A.

Bars Q₁, Q₂, Q₃ show drive currents of the FETs in cases where the semiconductor devices of the comparative examples shown in FIG. 3D to FIG. 3F are manufactured by single exposure based on the design data shown in FIG. 3A to FIG. 3C, respectively. Here, values of all drive currents expressed by the bars Q₁, Q₂, Q₃ are values obtained by dividing values of the drive currents of the FETs by a value of the drive current of the FET in the semiconductor device of the comparative example shown in FIG. 3D to be manufactured by single exposure.

Bars R₁, R₂, R₃ show drive currents of the FETs in cases where the semiconductor devices of the first embodiment shown in FIG. 1D to FIG. 1F are manufactured by single exposure based on the design data shown in FIG. 1A to FIG. 1C, respectively. Here, values of all drive currents expressed by the bars R₁, R₂, R₃ are values obtained by dividing values of the drive currents of the FETs by a value of the drive current of the FET in the semiconductor device of the first embodiment shown in FIG. 1D to be manufactured by single exposure based on the design data shown in FIG. 1A.

In the case of the double exposure indicated by the bars P₁ to P₃, when the number of first contact regions C₁ (hereinafter referred to as “contact region number”) per one source diffusion layer 4, or per one drain diffusion layer 5, is increased from 1 to 2, the drive current is increased 1.3 times. Further, in the case of the bars P₁ to P₃, when the contact region number is increased from 1 to 3, the drive current is increased 1.4 times.

On the other hand, in the case of single exposure in the comparative example indicated by bars Q₁ to Q₃, when the contact region number is increased from 1 to 2, the drive current is increased 1.1 times. Further, in the cases of the bars Q₁ to Q₃, when the contact region number is increased from 1 to 3, the drive current is increased 1.3 times.

In this manner, when the double exposure is replaced with single exposure of the conventional example, in the FET manufactured by single exposure, an irregular layout dependency, which is different from the layout dependency of the FET manufactured by double exposure, is generated. In this case, the design and an operation verification methodology of the FET manufactured by the double exposure method cannot be utilized in FETs manufactured by the single exposure method. Thus, it becomes necessary to perform the operation verification independently.

Further, in the case of the 28 nm generation, when such a problem exists, the design and an operation verification result of the FET of 32 nm generation manufactured by the single exposure cannot be utilized in FETs of the 28 nm generation which are manufactured by single exposure. Thus, it is necessary to perform the operation verification independently with respect to the 28 nm generation. Here, when the bars P₁, P₂, P₃ indicate operating characteristics of FETs of 28 nm, which are manufactured by double exposure under the same design environment as the 32 nm generation, the bars P₁, P₂, P₃ correspond with the operating characteristics of FETs of the 32 nm generation which are manufactured using single exposure.

Accordingly, in the first embodiment, as described previously, to allow one second contact region C₂ to have a function substantially equal to a function of two first contact regions C₁, the resistance of one second contact region C₂ is set to a value substantially equal to the resistance of two first contact regions C₁ which are connected to each other in parallel.

As a result, in the case of the single exposure in the first embodiment indicated by the bars R₁ to R₃, the layout dependency is substantially equal to the layout dependency when double exposure is performed, as indicated by the bars P₁ to P₃. According to the first embodiment, the design and an operation verification result of the FET manufactured by double exposure can be utilized with FETs manufactured by single exposure. Further, the design and the operation verification result of the FET of a 32 nm generation can be utilized by FETs of the 28 nm generation, which is the half-node generation of the 32 nm generation.

(4) Modification of First Embodiment

Next, a modification of the first embodiment is explained in conjunction with FIG. 5.

FIG. 5 is a plan view showing the structure of a semiconductor device according to the modification of the first embodiment.

In FIG. 5A, two first contact regions C₁ and two second contact regions C₂ are arranged on each of a source diffusion layer 4 and a drain diffusion layer 5. In this manner, in this modification, a plurality of first contact regions C₁ and a plurality of second contact regions C₂ may be arranged on each of the same source diffusion layer 4 and the same drain diffusion layer 5.

Here, on the source diffusion layer 4 shown in FIG. 5A, the first contact regions C₁ and the second contact regions C₂ are arranged alternately. In the same manner, on the drain diffusion layer 5 shown in FIG. 5A, the first contact regions C₁ and the second contact regions C₂ are arranged alternately. Such an arrangement has an advantageous effect that, compared with an arrangement where same kind of contacts are consecutively arranged adjacent to each other, makes it easy to balance an electric current or balance resistance in the source diffusion layer 4 and in the drain diffusion layer 5, for example.

In FIG. 5A, both the first contact regions C₁ on the source diffusion layer 4 are arranged adjacent to second contact regions C₂ on the drain diffusion layer 5, respectively, with a gate electrode 3 sandwiched therebetween. In the same manner, both the second contact regions C₂ on the source diffusion layer 4 are arranged adjacent to first contact regions C₁ on the drain diffusion layer 5, respectively, with the gate electrode 3 sandwiched therebetween. Such an arrangement has an advantageous effect that, compared with an arrangement where the same kind of contacts are arranged adjacent to each other with the gate electrode 3 sandwiched therebetween, it is easy to balance an electric current and balance resistances in the source diffusion layer 4 or in the drain diffusion layer 5, for example.

In FIG. 5B, a first contact region C₁ having a first size, a second contact region C₂ having a second size greater than the first size, and a third contact region C₃ having a third size greater than the second size are arranged on each of the source diffusion layer 4 and the drain diffusion layer 5. In this manner, according to this modification, three or more kinds of contact regions may be arranged on each of the same source diffusion layer 4 and the same drain diffusion layer 5. Here, the third contact region C₃ corresponds to an example of a second contact region in the case where the above-mentioned value of N is 3 or more.

In this embodiment, only two kinds of contacts may be used as source contacts 11 and drain contacts 12. Alternatively, three or more kinds of contact regions may be used as shown in FIG. 5B. However, by setting a low number of kinds of contact regions to be used, it is possible to acquire an advantageous effect that the manufacture of the semiconductor device becomes easier, which includes simplification of the preparation of the photo mask. When the number of kinds of contact regions to be used is small, for example, as shown in FIG. 1(F), the number of occasions where plural kinds of contact regions are arranged on the same source diffusion layer 4, or the same drain diffusion layer 5, is increased.

In this embodiment, in the replacement of the first contact regions C₁ with the second contact region C₂, the length X₂ and the length X₁ are set substantially equal to each other in length, and the width Y₂ is set longer than the width Y₁. As an alternative example, it may be possible to set these widths and lengths such that the length X₂ is set to be greater than the length X₁, and the width Y₂ and the width Y₁ are set to be substantially equal to each other. In this embodiment, it may be also possible to set these dimensions such that the length X₂ and the length X₁ differ from each other in length, and the size Y₂ and the size Y₁ differ from each other. For example, the area X₂Y₂ may be set to a value two times greater than the area X₁Y₁ by setting the length X₂ to a value √2 times as large as the length X₁ and by setting the width Y₂ to a value √2 times as large as the width Y₁. In these cases, however, it is desirable that the dimensions and the arrangement of the contact regions are determined such that the distance between the contact regions is set so as to allow single exposure methods, i.e., they are spaced so that irregular formation thereof does not occur.

Further, in this embodiment, although the number of the source contacts 11 which are arranged on the source diffusion layer 4 and the number of the drain contacts 12 which are arranged on the drain diffusion layer 5 are set equal, the number of the source contact 11 and the number of the drain contact 12 may be different from each other.

As described above, in this embodiment, in manufacturing the semiconductor device based on the design data, the first contact regions C₁ arranged on the source diffusion layer 4, or on the drain diffusion layer 5, are replaced with the above-mentioned second contact region C₂, thus manufacturing the semiconductor devices exemplified in FIG. 1E and FIG. 1F. According to this embodiment, in manufacturing the contact regions by replacing plural exposure methods to a single exposure method, it is possible to suppress irregular layout dependency.

Second Embodiment

FIG. 6 is a flowchart showing a manufacturing method of a semiconductor device according to one embodiment. FIG. 6 shows one example of steps for manufacturing the semiconductor devices shown in FIG. 1D to FIG. 1F based upon the design data shown in FIG. 1A to FIG. 1C.

Firstly, design data for manufacturing the semiconductor device having the structure shown in FIG. 1A to FIG. 1C is prepared (step S1).

Next, a photo mask is prepared based on the design data (step S2). Here, in handling the design data shown in FIG. 1A, a photo mask for single exposure is prepared for manufacturing a semiconductor device which exactly complies with the design data. On the other hand, in handling the design data shown in FIG. 1B or FIG. 1C, a photo mask for single exposure is prepared by replacing two first contact regions C₁ arranged on the same source diffusion layer 4, or on the same drain diffusion layer 5, with one second contact region C₂.

Next, a semiconductor device is manufactured using the above-mentioned photo mask (step S3). Here, source contacts 11 or drain contacts 12 can be manufactured by single exposure. In this manner, the semiconductor devices shown in FIG. 1D to FIG. 1F are manufactured based on the design data shown in FIG. 1A to FIG. 1C respectively.

As described above, according to this embodiment, not only in the handling of the design data shown in FIG. 1A, but also in the handling of design data shown in FIG. 1B or FIG. 1C, it is possible to manufacture the source contact 11 and the drain contact 12 by single exposure. In this embodiment, by performing the replacement of the first contact region C₁ with the second contact region C₂ in the same manner as the first embodiment, it is possible to suppress the generation of the above-mentioned irregular layout dependency.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. 

What is claimed is:
 1. A semiconductor device, comprising: a substrate; a gate electrode formed above the substrate; a source diffusion layer and a drain diffusion layer which are formed within the substrate sandwiching the gate electrode therebetween; one or more source contacts formed on the source diffusion layer; and one or more drain contacts formed on the drain diffusion layer, wherein at least one of the source contacts and drain contacts includes a first contact region having a first contact region having a first size and a second contact region having a second size greater than the first size on at least one of the same source diffusion layer and on the same drain diffusion layer.
 2. The semiconductor device according to claim 1, wherein a resistance of the second contact region is 0.9 times to 1.1 times a resistance of N (N being an integer of 2 or more) first contact regions which are connected to each other in parallel.
 3. The semiconductor device according to claim 1, wherein the semiconductor device is a 28 nm node generation or a node generation following the 28 nm node generation.
 4. The semiconductor device according to claim 1, wherein the first contact region and the second contact region are alternately arranged on the at least one of the source diffusion layer and the drain diffusion layer.
 5. The semiconductor device according to claim 1, wherein the first contact region formed on the source diffusion layer is arranged adjacent to the second contact region formed on the drain diffusion layer with the gate electrode sandwiched therebetween.
 6. The semiconductor device according to claim 1, wherein the second contact region formed on the source diffusion layer is arranged adjacent to the first contact formed on the drain diffusion layer with the gate electrode sandwiched therebetween.
 7. The semiconductor device according to claim 1, wherein the first contact region formed on the source diffusion layer is arranged adjacent to the second contact region formed on the drain diffusion layer with the gate electrode sandwiched therebetween, and the second contact region formed on the source diffusion layer is arranged adjacent to the first contact formed on the drain diffusion layer with the gate electrode sandwiched therebetween.
 8. The semiconductor device according to claim 1, wherein a third contact region having a third size greater than the second size is formed on the at least one of the same source diffusion layer and on the same drain diffusion layer.
 9. The semiconductor device according to claim 8, wherein the first contact region formed on the source diffusion layer is arranged adjacent to the third contact region formed on the drain diffusion layer with the gate electrode sandwiched therebetween.
 10. The semiconductor device according to claim 8, wherein the first contact region formed on the drain diffusion layer is arranged adjacent to the third contact region formed on the source diffusion layer with the gate electrode sandwiched therebetween.
 11. The semiconductor device according to claim 8, wherein the first contact region, the second contact region and the third contact region are alternately arranged on the at least one of the source diffusion layer and the drain diffusion layer.
 12. A semiconductor device, comprising: a substrate; a source diffusion layer and a drain diffusion layer provided on the substrate and spaced from one another a gate electrode disposed on a gate insulation film disposed on the substrate, different portions of the gate electrode overlying the source region and the drain region; one or more source contacts provided on the source diffusion layer; and one or more drain contacts provided on the drain diffusion layer, wherein at least one of the source contacts and the drain contacts includes a first contact having a first size and a second contact having a second size greater than the first size located on at least one of a single source diffusion layer and a single drain diffusion layer.
 13. The semiconductor device according to claim 12, wherein the resistance of the second contact region is 0.9 times to 1.1 times the resistance of N (N being an integer of 2 or more) first contact regions connected to each other in parallel.
 14. The semiconductor device according to claim 12, wherein the semiconductor device is a 28 nm node generation or a node generation following the 28 nm node generation.
 15. The semiconductor device according to claim 12, wherein the first contact and the second contact are alternately arranged on at least one of the single source diffusion layer and the single drain diffusion layer.
 16. The semiconductor device according to claim 12, wherein the first contact disposed on the source diffusion layer is adjacent to the second contact disposed on the drain diffusion layer.
 17. A semiconductor device, comprising: a substrate; a gate electrode disposed on a gate insulation film disposed on the substrate; a source diffusion layer and a drain diffusion layer provided on the substrate the gate electrode extending therebetween; source plurality of contacts provided on at least one of the source diffusion layer and the drain diffusion layer, wherein at least one of the one or more contacts disposed on at least one of the source and the drain regions include at least two contacts having different areas of contact with the source or drain region.
 18. The semiconductor device according to claim 17, wherein the at least two contacts comprise a length and a width in contact with the source or drain region; the contacts have the same length and different widths; and the gate electrode is spaced the two contacts in the source or drain regions and extends in the width direction.
 19. The semiconductor device according to claim 17, wherein the at least two contacts comprise a length and a width in contact with the source or drain region; the contacts have the same length and different widths; and the gate electrode is spaced the two contacts in the source or drain regions and extends in the length direction.
 20. The semiconductor device according to claim 17, further including: a third contact region having a third area in contact with the source or drain region with which the first and second contacts contact, the third area greater than the contact area of both the first and the second contacts with the source or drain region. 